doc: raw1394: Trivial typo fix

	/dev/raw1394 was a character device file that allowed low-level

	access to FireWire buses.  Its major drawbacks were its inability

	to implement sensible device security policies, and its low level

	of abstraction that required userspace clients do duplicate much

	of abstraction that required userspace clients to duplicate much

	of the kernel's ieee1394 core functionality.

	Replaced by /dev/fw*, i.e. the <linux/firewire-cdev.h> ABI of

	firewire-core.